This invention relates to the presentation of at least two different sets of information to an observer simultaneously and at the same location, one set being superposed upon the other, one set of information concerning characters inscribed on a source carrier or document, the other set being produced by a data processing machine. According to the invention the latter information is displayed in juxtaposition to the source data carrier and the visually displayed operator instructions. In prior arrangements the display is located remotely from the document thus entailing considerably eye and head movements of the operator.
The source data will have been inscribed on the data carrier or document by an originator. The machine instructions to the operator concerning the keying of this source data may be indicated by means of small diameter light sources in juxtaposition to the document so that each instruction is visible to the viewer as information superposed by being positioned immediately above the inscribed data. Neither set of data interferes with the other. The localized document area on which characters are inscribed and of interest to the viewer, at any particular time during the operation, is one document line containing one or more fields to be keyed in. It is seen in document context by the operator. The machine produced information which marks the fields on the line and to be keyed in consists of luminous markers of contrasting color to the non-illuminated area of the document containing the data to be keyed. In addition alpha/numeric computer feedback information may be displayed immediately above these luminous markers.